(USA TODAY) -- A photographer who saw a man pushed onto subway tracks and shot pictures moments before he was killed by a train says he was using the camera's flash to warn the driver to stop the train.

R. Umar Abbasi, a freelance photographer for the New York Post, told the newspaper he was waiting for a train Monday when he saw KI Suk Han, 58, pushed onto the tracks. "I just started running, running, hoping that the driver could see my flash," Abbasi told the Post.

The Post published a front-page photo of Han on the tracks, apparently trying to climb onto the platform, with the moving train just feet away. Abbasi said Han tried to scramble back to the platform as onlookers screamed for the train driver to stop. The train slowed, but Han could not escape.

Abbasi said the train "crushed him like a rag doll."

"The most painful part was I could see him getting closer to the edge. He was getting so close," he told the Post. "And people were running toward him and the train.

Abbasi said he would have been unable to pull the man to safety. Still, his actions drew outrage from many on Twitter. Among tweets:

-- Matt Jordan (@infamousmj) "The photog should be arrested. He should have helped him."

Physician Laura Kaplan was on the platform when the tragedy occurred and told the Post she had a stethoscope and rushed over to help the dying man. "People were shouting and yelling when it happened, but then people ran the other way," Kaplan, 27, told the Post. "I heard what I thought were heart sounds," she said, but Han never took a breath.

A manhunt was underway for the killer, described by police as black, 30 to 40 years old, about 5-foot-9, with short dreadlocks. He was wearing a white T-shirt, dark jacket, jeans, black sneakers with a white stripe and a black beanie cap.